Many efforts to meet various customers' needs have been made in fields of an automotive industry and one of the fields is a surface treatment and painting to an aluminum wheel for an automobile. The aluminum wheel has an elegant appearance and easy operability of steering wheel due to a light weight when travelling. In addition, the aluminum wheel has function of protecting a tire from overheat since it has high thermal conductivity and thus heat generated from the tire due to friction with the ground when travelling is quickly exhausted. However, the aluminum wheel has disadvantages that its surface is rough since it is manufactured by casting and it has low corrosion resistance and low abrasion resistance due to its own properties.
To treat a surface of the aluminum wheel having functionally superior effect is used a surface treatment by electrolytic plating of the aluminum wheel surface using chromium, by which luxury surface gloss and high reflectivity can be obtained and abrasion resistance, which does not easily permit a generation of scars, is superior due to a high hardness, whereas cost for plating treatment is excessively taken and there are problems of air pollution and waste water during plating process because the aluminum wheel having a rough surface should be polished several times. Therefore, an import and export of an automobile coated with hexavalent chromium having CrO3 as a main element is forbidden in the world including U.S. and E.U. Meanwhile, a treatment method in which the surface of the aluminum is vacuum deposited using a metal such as a silver(Ag), a nickel(Ni), a titanium(Ti) and so on is also used, however there are problems that a chamber of a high vacuum is required, a shape and a size of the wheel is limited, a coating thickness is uneven and an equipment cost is high.
Therefore, continuous effort of the present inventors to solve the above problems results successfully in an approach to the present invention. In other words, the present invention, through continuous experiments, provides a method for manufacturing an aluminum wheel, in which the aluminum wheel shows various metal textures and has a superior gloss, a process is relatively simple and a manufacturing cost is inexpensive.